ROLE OF STEP, A STRIATAL ENRICHED TYROSINE PHOSPHATASE, IN NEURONAL CELL DEATH

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In our initial project we proposed to test the hypothesis that STEP, a striatal enriched tyrosine phosphatase plays a critical role in neuronal cell death by regulating the temporal activity of p38 and ERK MAP kinase signaling pathway. Previously we have demonstrated that STEP could only bind to p38a and p38b isoforms, which are expressed in the brain. In contrast STEP cannot bind to or co-immunoprecipitate p38g and p38d isoforms. In vitro phosphatase assay showed that wild type STEP can bind to and dephosphorylate p38a isoform. Immunohistochemical approaches showed that STEP and p38a MAP kinase are co-localized in striatal neurons. We also established an animal model of transient focal ischemia, characterized by loss of oxygen and glucose to a part of the central nervous system, through the occlusion of the right carotid artery.